| In this study,1hm2 artificial mixed forest permanent sample plot in the Wuling Mountain Rocky Desertification Comprehensive Management Research Base in Xiangxi Autonomous Prefecture of Hunan Province was selected as the research object,and 600 soil samples at 0-15cm,15cm-30cm,and 30cm-50cm under the vertical section were collected in the study area..Descriptive statistical analysis,correlation analysis principal component analysis of the soil characteristics in the study area are carried out using classical statistics.The semi variance function model in geostatistics and the Kriging spatial interpolation method were used to analyze the spatial structure and distribution pattern of soil physical and chemical properties.This study combined the rocky desertification background to deeply explore the soil properties and spatial heterogeneity of artificial mixed forests in karst rocky desertification areas,and obtained the following results:(1)The results of descriptive statistical analysis show that:a)The physical and chemical properties of the soil in the vertical section increase with the depth of the soil,and the bulk density of the soil gradually increases.The soil water content,soil porosity and water holding capacity generally decrease with the increase of the soil depth.The pH value of the soil increases with the depth of the soil layer.The change in the soil remained largely unchanged,the content of organic matter,total nitrogen,and total phosphorus decreased.In particular,the content of soil organic matter decreased sharply with the increase of soil depth,and the content of total potassium in the soil increased with the increase of soil depth.b)According to the different physical and chemical properties of the soil,the degree of variation of the physical and chemical properties of the soil is also different.The coefficient of variation of the physical and chemical properties of the soil ranges from 0.1 to 0.74.The variation of soil bulk density and pH value is very weak.The variation of soil moisture content,soil non-capillary porosity,and organic matter is relatively high,and the rest are moderately variable.c)Compared with the abandoned land,the soil physical and chemical properties of the artificial mixed forest in the study plot are mainly expressed in the artificial mixed forest soil volume is larger than the abandoned land,the water holding capacity is less than the abandoned land,the soil porosity is not much different,organic matter,total nitrogen,total phosphorus The content is less than that of abandoned land,and the total potassium content is higher than that of abandoned land.d)The content of soil physical and chemical properties is different under different rocky desertification degrees.Soil bulk density and pH content showed the order of extreme rocky desertification>severe rocky desertification>moderate rocky desertification>light rocky desertification.The organic matter content under 0-15cm all showed the order of moderate>extremely severe rocky desertification>slightly rocky desertification>severe rocky desertification.The other soil physical and chemical properties under different rocky desertification levels are in the order of mild rocky desertification>moderate rocky desertification>severe rocky desertification>very severe rocky desertification.There are significant differences in the content of soil physical and chemical properties under different rocky desertification degrees.(P<0.05).(2)The results of correlation analysis show that:a)There is a very significant negative correlation between soil bulk density and soil water content,capillary water holding capacity,maximum water holding capacity,and minimum water holding capacity(P<0.01),and a significant negative correlation with capillary porosity and total porosity(P<0.05).There is a very significant negative correlation between soil pH and total soil phosphorus content(P<0.01),and a very significant positive correlation with total potassium content(P<0.01).The content of soil organic matter has a very significant positive correlation with the total nitrogen and total phosphorus content of the soil(P<0.01),and a significant negative correlation with the total potassium content(P<0.05).b)The soil under different vertical profile depths also has a certain correlation.The overall performance is the correlation between layer B(15cm-30cm)&layer C(30cm-50cm)>layer A(0cm-15cm)&layer B(15cm)The correlation between-30cm)>The correlation between layer A(0cm-15cm)&layer C(30cm-50cm).(3)The results of principal component analysis show that:Four principal components were extracted from soil physical and chemical properties.The cumulative variance contribution rate of the four principal components is 95.557%In this study,a lhm2 artificial mixed forest permanent sample plot in the Wuling Mountain Rocky Desertification Comprehensive Management Research Base in Xiangxi Autonomous Prefecture of Hunan Province was selected as the research object,and 600 soil samples at 0-15cm,15cm-30cm,and 30cm-50cm under the vertical section were collected in the study area..Descriptive statistical analysis,correlation analysis and principal component analysis of the soil characteristics in the study area are carried out using classical statistics.The semivariance function model in geostatistics and the Kriging spatial interpolation method were used to analyze the spatial structure and distribution pattern of soil physical and chemical properties.This study combined the rocky desertification background to deeply explore the soil properties and spatial heterogeneity of artificial mixed forests in karst rocky desertification areas,and obtained the following results:(1)The results of descriptive statistical analysis show that:a)The physical and chemical properties of the soil in the vertical section increase with the depth of the soil,and the bulk density of the soil gradually increases.The soil water content,soil porosity and water holding capacity generally decrease with the increase of the soil depth.The pH value of the soil increases with the depth of the soil layer.The change in the soil remained largely unchanged,the content of organic matter,total nitrogen,and total phosphorus decreased.In particular,the content of soil organic matter decreased sharply with the increase of soil depth,and the content of total potassium in the soil increased with the increase of soil depth.b)According to the different physical and chemical properties of the soil,the degree of variation of the physical and chemical properties of the soil is also different.The coefficient of variation of the physical and chemical properties of the soil ranges from 0.1 to 0.74.The variation of soil bulk density and pH value is very weak.The variation of soil moisture content,soil non-capillary porosity,and organic matter is relatively high,and the rest are moderately variable.c)Compared with the abandoned land,the soil physical and chemical properties of the artificial mixed forest in the study plot are mainly expressed in the artificial mixed forest soil volume is larger than the abandoned land,the water holding capacity is less than the abandoned land,the soil porosity is not much different,organic matter,total nitrogen,total phosphorus The content is less than that of abandoned land,and the total potassium content is higher than that of abandoned land.d)The content of soil physical and chemical properties is different under different rocky desertification degrees.Soil bulk density and pH content showed the order of extreme rocky desertification>severe rocky desertification>moderate rocky desertification>light rocky desertification.The other soil physical and chemical properties under different rocky desertification levels are in the order of mild rocky desertification>moderate rocky desertification>severe rocky desertification>very severe rocky desertification.e)There is no significant difference in soil water holding capacity and porosity under different rocky desertification degrees.The soil bulk density,pH value,organic matter,nitrogen,phosphorus,and potassium under different rocky desertification degrees are mainly manifested as mild rocky desertification and severe and extremely severe rocky desertification have significant differences(P<0.05).(2)The results of correlation analysis show that:a)There is a very significant negative correlation between soil bulk density and soil water content,capillary water holding capacity,maximum water holding capacity,and minimum water holding capacity(P<0.01),and a significant negative correlation with capillary porosity and total porosity(P<0.05).There is a very significant negative correlation between soil pH and total soil phosphorus content(P<0.01),and a very significant positive correlation with total potassium content(P<0.01).The content of soil organic matter has a very significant positive correlation with the total nitrogen and total phosphorus content of the soil(P<0.01),and a significant negative correlation with the total potassium content(P<0.05).b)The soil under different vertical profile depths also has a certain correlation.The overall performance is the correlation between layer B(15cm-30cm)&layer C(30cm-50cm)>layer A(0cm-15cm)&layer B(15cm)The correlation between-30cm)>The correlation between layer A(0cm-15cm)&layer C(30cm-50cm).(3)The results of principal component analysis show that:Four principal components were extracted from soil physical and chemical properties.The cumulative variance contribution rate of the four principal components is 95.557%.The main components of soil organic matter,nitrogen,phosphorus,potassium,and porosity have large weight coefficients,which are the key factors of soil physical and chemical properties,which play an important role in the formation and stability of soil structure and the improvement of soil nutrient cycling.effect.(4)The results of geostatistical analysis show:a)The spatial range of soil physical and chemical properties at different vertical profile depths is between 21.91m-87.59m.The spatial autocorrelation range of soil bulk density,soil water content,soil non-capillary porosity,capillary water holding capacity,and maximum water holding capacity under different depth soil layers has a large variation.b)The optimal semi-variance function fitting model of soil physical and chemical properties mainly includes exponential model,spherical model and Gaussian model.The physical and chemical properties of the soil abutment ratio Co/Co+C ranges from 12.99%-89.53%,and the A layer(0cm-15cm)has a high degree of spatial dependence on pH,total phosphorus,and total potassium.Layer A(0cm-15cm)soil total porosity and maximum water holding capacity,layer B(15cm-30cm)organic matter,layer C(30cm-50cm)total nitrogen,and minimum water holding capacity have a weak spatial dependence.c)Use the kriging interpolation in ArcGIS to estimate the physical and chemical properties of the unsampled points,draw the spatial distribution pattern of the soil physical and chemical properties,and find that the physical and chemical properties of the soil are spatially distributed with different sizes and shapes.Plaque.The degree of rocky desertification is an important factor affecting the spatial distribution pattern of soil physical and chemical properties.Therefore,the high value areas of various indexes of soil physical and chemical properties are mostly distributed in the central and eastern parts of the study area where the degree of rocky desertification is relatively light.Although the spatial distribution patterns of soil at different depths have their own characteristics,there is a certain degree of consistency. |
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